一元三次方程求解 实数二分

Posted 2021-05-23 幽殇默

https://ac.nowcoder.com/acm/problem/16694

#include<cstdio>
#include<iostream>
using namespace std;
double a,b,c,d;
double check(double x)
{
	return a*x*x*x+b*x*x+c*x+d;
}
int main(void)
{
	cin>>a>>b>>c>>d;
	for(int i=-100;i<=100;i++)
	{
		double l=i,r=i+1;
		if(check(l)==0) printf("%.2lf ",l);
		else if(check(l)*check(r)<0)
		{
			while(r-l>0.0001)
			{
				double mid=(l+r)/2;
				if(check(mid)*check(l)<=0) r=mid;
				else l=mid;
			}
			printf("%.2lf ",l);
		}
	}
	return 0;
}